In Situ Mixed Region Vapor Stripping in Low-Permeability Media. 1. Process Features and Laboratory Experiments

摘要

This is the first paper in a three-part series on mixed region vapor stripping (MRVS) for in situ treatment of fine-grained soils contaminated by volatile organic compounds (VOCs). In this paper, the MRVS process is described followed by the results of laboratory experiments in which the efficiency of MRVS for removing trichloroethene (TCE) was measured. These experiments revealed that MRVS could rapidly remove > 90% of the initial TCE from fine-grained, silty clay soils ( > 80% silt and clay particles, and hydraulic conductivity < 10~(-6) cm s~(-1)). A spherical diffusion model for TCE mass removal during MRVS was developed and used to simulate the measured reductions in soil TCE level as a function of treatment time. The conceptual model for VOC transport was subsequently used to simulate VOC removals measured in the MRVS field tests. The field-scale evaluation of MRVS is the subject of the second paper, while model simulations of field VOC removals are described in the third paper in this series.